Long-range two-body final-state interactions and direct CP asymmetry in {B}^{+}\to{\pi}^{+} {K}^{0} decay

Abstract

We present a calculation of the direct CP asymmetry, $A_{CP}^{dir}$, for the process $B^{+}\to {\pi }^{+}{K}^0$ including the effects of long-range inelastic final-state interactions (FSI). We admit three channels in our calculation: $B^{+}\to ({\pi }^{+}{K}^0),(\eta K^{+})$, and $(D_s^{+}{\bar{D}}^0)$. The strong scattering is described in terms of Pomeron and Regge exchanges. We find that the direct CP asymmetry is enhanced by a factor of $\sim 3$ as a result of FSI, but remains well short of the claims of (10 - 20)% in recent literature. A critical assessment of papers claiming large CP asymmetries is also presented.

Comments: 21 pages, latex, no figures. Added the charge-exchange channel {B}^{+}\to {\pi}^{0} {K}^{+}. Expanded the discussion section. To be published in Phys. Rev. D